1. Field of the Invention
This invention relates to a method and apparatus for installing and removing valve stems from the valve stem opening defined by a vehicular wheel or rim. The apparatus for installing the valve stem both compresses the anchoring portion of the valve stem and simultaneously forces the valve stem under fluid pressure into the valve stem opening. Such valve stems can be readily removed from the opening by the insertion of the shaft of the valve stem removal tool through the central, axial portion of the valve stem, engaging a hook or grasping member into the anchoring portion of the valve stem and pulling the valve stem from the opening. The method for installing and removing valve stems disclosed herein utilizes each of these apparatuses.
2. Description of the Prior Art
With the advent of tubeless tires, the problem of providing suitable means to inflate the tire arose, since the elimination of the inner tube also eliminated the valve carried by the inner tube. To overcome this problem, valve stems were developed. The universal acceptance of tubeless tires has led to the utilization of a valve stem of basic or conventional configuration. This "conventional" valve stem includes an elastic, bulbous base portion which defines an annular channel. Bonded to this base portion is an upstanding metal cylinder housing the internal components of the valve. When these valve stems were first utilized, they were installed using simple-hand tools. Because of the bulbous shape of the base portion, which tapers upwardly toward the cylinder, these valve stems were originally installed by hand by removing the tubeless tire from the rim or by separating the tire side wall from the rim, and inserting the valve stem into the opening from the inner side of the wheel or rim wall. The upwardly tapering base portion facilitated the installation of the valve stem from the inner side wall. The valve stem was then grasped with a common hand tool, such as pliers, and pulled outwardly until the channel engaged the side wall of the rim defining the valve stem opening. Hand installation of the valve stems from the outside of the rim is very difficult to accomplish because of the rounded or bulbous shape of the valve stem opposite the tapered portion of the base.
Because of the time and labor required to break the tire bead, remove the inoperable valve stem from the inside of the rim and install the new valve stem from the inside of the rim, various devices were developed to install the valve stem from the outside of the rim. The basic principle of each of these devices is to compress the rounded, bulbous portion of the valve stem base while ramming the valve stem through the opening from the outside of the rim. U.S. Pat. No. 3,750,258 to Sampo discloses a hand powered insertion tool for tire valve stems. Although this tool compresses the valve stem base and forces the valve stem into the opening from the outside, a significant drawback is that the operator must align the tool with the opening and attempt to simultaneously compress the base and force the valve stem axially through the tool by ramming a handle downwardly and at an angle. Practically, this tool will not perform satisfactorily. U.S. Pat. No. 4,765,048 to Hokanson discloses a power assisted tool similar in design to that disclosed in the '258 patent. The principal difference is that the shaft portion is externally threaded to communicate with internal threads of an end cap. As the shaft is manually rotated, it is forced axially through the tool by the interaction of the threads. The valve stem retained on the lower portion of the shaft is then compressed and forced incrementally from the tool and into the valve stem opening. This tool has the drawback of manual operation which additionally leads to excess installation time and labor cost. Further, the valve stem, being compressed between the insertion tool side walls and the shaft, may turn with the shaft causing wear on the valve stem during insertion. Another valve stem inserter was recently developed and disclosed in U.S. Pat. No. 4,807,343 to Wadsworth. This inserter utilizes the components of a conventional caulking gun, and incrementally forces a push rod through the gun as a lever is manually biased. The valve stem is mounted to the end of the push rod and compressed by being forced through the tapering side wall of the barrel of the tool. The drawbacks of this device include the increased installation time resulting from the manual operation, the difficulty in applying force to the lever or trigger, and the incremental advancement of the valve stem which not only add to installation time and labor cost but can add to the stress or wear on the valve stem itself.
Further, these prior art devices do not disclose a method for removal of the used or inoperable valve stems prior to the insertion of the new valve stem. This is obviously a first step which must be accomplished prior to inserting a new valve stem in a previously inflated tubeless tire. Often in the prior art, the tire was removed from the rim or its side walls separated from the rim in order to pull the inoperable valve stem internally from the opening. This obviously negates the supposed advantage of the installation methods described in the prior art. Another frequently used method of removal is to insert a common tool, such as a screwdriver, between the bulbous, base portion of the valve stem and the rim side wall defining the opening, and attempting to force the valve stem outwardly using leverage. This often damages the opening, adversely affecting the seal of the subsequently installed valve stem. Still another method in the prior art used to remove inoperable valve stems is to grasp the cylindrical portion of the valve stem and pull the valve stem outwardly with enough force to rip the stem from the wheel. In this case, the bulbous, lower portion of the valve stem often shears from the upper portion and falls into the installation chamber between the tubeless tire and the wheel. This can cause, among other problems, difficulty in obtaining a perfect balancing of the wheels. This problem is increased as more valve stems are removed in this fashion.
The present invention overcomes many of the disadvantages of valve stems inserters of the prior art. As disclosed herein, the inserter of the present invention permits quick and certain valve stems installation, which can be accomplished by an individual of any strength, since the insertion tool does not require manual force for its actuation.